This invention relates to improved chlorinated polyolefin elastomer curable compositions which contain relatively high levels of additives.
Chlorinated polyethylene elastomers and chlorinated ethylene copolymer elastomers have been found to be very good elastomeric materials for use in applications such as wire and cable jacketing, molded goods and automotive hose.
Curable compositions of these elastomers generally contain various types of additives such as fillers, plasticizers, processing aids and acid acceptors in order to render the compositions more suitable for a particular application. The maximum amount of an additive which may be incorporated into a curable elastomer composition is determined by the point at which no additional additive may be introduced without causing a parameter (e.g. tensile strength, elongation, conductivity, etc.) of the cured composition to fall outside of the specifications for a particular end use application. However, it is sometimes desirable to further increase the amount of an additive in such curable compositions in order to improve a different parameter (e.g. processability of the composition or a different physical property of the cured composition), or to reduce the cost of the composition. Therefore, there is a need for a chlorinated polyolefin elastomer composition which can incorporate higher levels of additives than has been possible heretofore, without causing one or more parameters of the cured composition to fall outside of specifications.
It has been surprisingly discovered that curable chlorinated olefin elastomer compositions, containing a higher level of additives than was possible in the past, can be prepared from certain very high molecular weight elastomers. Cured articles prepared from these compositions have excellent elastomeric physical properties and readily pass industry testing standards such as Underwriters Laboratory (UL) 62 specifications for elastomers to be used in wire and cable jacketing.
One aspect of the present invention is specifically directed to an improved curable elastomer composition comprising: A) a chlorinated olefin elastomer having a chlorine content of from 15-48 percent by weight; said chlorinated olefin elastomer being prepared from an olefin polymer selected from the group consisting of i) polyethylene homopolymers having I10 values of from 0.05-0.8 dg/minute and ii) copolymers of ethylene and up to 25 weight percent of a copolymerizable monomer, said copolymers having I10 values of from 0.05-0.8 dg/minute; and B) at least 300 phr of an additive package.
Another aspect of the present invention is a jacket for wire and cable. The jacket is made from a cured elastomer composition comprising A) a chlorinated olefin elastomer having a chlorine content of from 15-48 percent by weight; said chlorinated olefin elastomer being prepared from an olefin polymer selected from the group consisting of i) polyethylene homopolymers having I10 values of from 0.05-0.8 dg/minute and ii) copolymers of ethylene and up to 25 weight percent of a copolymerizable monomer, said copolymers having I10 values of from 0.05-0.8 dg/minute; and B) at least 300 phr of an additive package.